I'm sure it really does depend on exactly what you're shooting at night. But for me, walking around on city streets with average sort of street lamps and stuff, I'm always good with my 400 speed and my 50mm 1.7 lens. I'll shoot wide open and hand held the shots with 1/30, 1/15, or 1/8 shutter speeds with pretty good results most of the time. Sometimes I'll steady myself against a pole or building if need be.